• 한국의류학회지
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• 제35권10호
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• pp.1188-1198
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• 2011

This study proposes the use of firework shapes to design fashion accessories in the judgment that they are appropriate for the expression of creative images in consideration of the display of fireworks as a kind of entertainment and a festive symbol. This study promotes the sustainable application of firework shapes to develop the designs of fashion culture items that feature a distinctive personality and uniqueness. In this present study, the proposed fashion accessory design was intended to create an entertaining new atmosphere that uses an Organic Light Emitting Diode (OLED) that draws attention as a futuristic display. In terms of methodology, a literature review of firework shapes and OLED was conducted; in addition, Adobe Illustrator CS2 and Adobe Photoshop CS2 were used to develop six different standard motive designs with formative design elements represented by a variety of firework shapes. Each of the six motifs was further expanded with different color combinations. Rich images are produced with the use of pink, blue, purple, green, yellow, orange, and red, in conjunction with various OLED effects to express the three-dimensional images of fireworks. The motifs are applied to three types of items: bags, bracelets, and necklaces. For the video images, evening and tote bags, pendants, and bangles were used. Shifting images and lights should produce unique images as well as satisfy the consumer desire for entertainment. The Adobe Image Ready software was used to present the motive of fireworks applied to the design of fashion accessories in video images but not in still-cut images due to physical constraints of this paper.

• 기술혁신학회지
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• 제14권spc호
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• pp.1152-1170
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• 2011

본 연구에서는 기술문서의 인용 정보를 기반으로 직접인용과 간접인용을 고려하여 핵심 문서를 선별하였고 선별된 문서 간의 인용네트워크 트리(citation network tree)를 생성하여 기술진화 경로를 추출하고자 하였다. 활용 예시로 OLED(유기발광다이오드) 분야 특허데이터를 분석하여 핵심문서를 선별한 후 문서간 인용관계 트리 계보도를 생성하였고, 그 중 OLED 원천기술이 어떤 기술진화 경로를 통해 반도체 관련 기술로 전이되었는지 분석하였다. 다른 한편으로 그래핀(graphene) 분야 논문의 인용관계 트리 분석을 통하여 간접인용을 고려한 가중치 계산방법이 직접인용만을 고려한 피인용 회수 계산법보다 현실을 더 잘 반영함을 고찰하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 제37회 하계학술대회 논문집 C
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• pp.1295-1296
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• 2006

수소화된 비정질 실리콘 박막 트랜지스터(a-Si:H TFT)의 이력 현상이 능동형 유기 발광 다이오드(Active-Matrix Organic Light Emitting Diode) 디스플레이 패널을 구동할 경우에, 발생할 수 있는 잔상(Residual Image) 문제를 단위 소자 및 회로에서 실험을 통하여 규명하였다. 게이트 시작 전압을 바꾸어 VGS-ID 특성을 측정할 경우, 게이트 시작 전압이 5V에서 시작한 VGS-ID 곡선이 10V에서 시작한 VGS-ID 곡선에 비해 왼쪽으로 0.15V 이동하였다. 이러한 결과는 게이트 시작 전압의 차이에 의해 발생한 트랩된 전하량(Trapped Charge) 변화로 설명할 수 있다. 또한, 인가하는 게이트 전압 간격을 0.5V에서 0.05V로 감소시켰을 때 전하 디트래핑 비율의 변화(Charge De-trapping Rate)로 인하여, 이력 현상(Hysteresis Phenomenon)으로 인한 단위 소자에서의 문턱전압의 변화가 0.78V에서 0.39V로 감소함을 관찰하였다. 제작된 2-TFT 1-Capacitor의 ANGLED 화소에서 (n-1)번째 프레임에서의 OLED 전류가 (n)번째 프레임에서의 OLED 전류에 35%의 전류오차를 발생시키는 것을 측정 및 분석하였다.

• 공업화학
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• 제34권6호
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• pp.633-639
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• 2023

We synthesized 2-(10-methyl-10H-phenothiazin-3-yl)-5-phenyl-1,3,4-oxadiazole (MPPO) and 5,5-(10-methyl-10H-phenothiazin-3,7-diyl)-bis-(2-phenyl-1,3,4-oxadiazole) (DPPO). MPPO has both electron-donating and electron-accepting substituents with asymmetric molecular geometry. By incorporating one extra electron-accepting group into MPPO, we created a symmetric molecule, which is DPPO. The optical and electrochemical properties of these compounds were measured. The lowest unoccupied molecular orbital (LUMO) level of DPPO was lower than that of MPPO. The excited-state dipole moment of DPPO, with symmetric geometry, was calculated to be 4.1 Debye, whereas MPPO, with asymmetric geometry, had a value of 7.0 Debye. The charge-carrier mobility of both compounds was similar. We fabricated non-doped organic light-emitting diodes (OLEDs) using D-A type molecules as an emitting layer. The current efficiency of the DPPO-based device was 7.8 cd/A, and the external quantum efficiency was 2.4% at 100 cd/m², demonstrating significantly improved performance compared to the MPPO-based device. The photophysical and electroluminescence (EL) characteristics of the two D-A type molecules showed that molecular symmetry, as well as the lowered LUMO level of DPPO, played critical roles in the enhancement of EL performance.

• 반도체디스플레이기술학회지
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• 제12권2호
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• pp.13-17
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• 2013

In lighting system where several large-area organic light-emitting diode (OLED) lighting panels are involved, panel aging may appear differently from each other, resulting in a falling-off in lighting quality. To achieve uniform light output across large-area OLED lighting panels, we have employed an optical feedback circuit. Light output from each OLED panel is monitored by the optical feedback circuit that consists of a photodiode, I-V converter, 10-bit analogdigital converter (ADC), and comparator. A photodiode generates current by detecting OLED light from one side of the glass substrate (i.e., edge emission). Namely, the target luminance from the emission area (bottom emission) of OLED panels is monitored by current generated from the photodiode mounted on a glass edge. To this end, we need to establish a mapping table between the ADC value and the luminance of bottom emission. The reference ADC value corresponds to the target luminance of OLED panels. If the ADC value is lower or higher than the reference one (i.e., when the luminance of OLED panel is lower or higher than its target luminance), a micro controller unit (MCU) adjusts the pulse width modulation (PWM) used for the control of the power supplied to OLED panels in such a way that the ADC value obtained from optical feedback is the same as the reference one. As such, the target luminance of each individual OLED panel is unchanged. With the optical feedback circuit included in the lighting system, we have observed only 2% difference in relative intensity of neighboring OLED panels.

• 반도체디스플레이기술학회지
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• 제21권2호
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• pp.25-31
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• 2022

By an aid of needle coating, we have fabricated a spherical microlens array using poly(methyl methacrylate) for potential applications in light extraction of organic light-emitting diodes. With an attempt to achieve high-density and high-aspect-ratio microlens arrays, we have investigated the coating behaviors by varying the material parameters such as the solute concentration and wettability of the poly(methyl methacrylate) solution and process parameters such as the dwell time of needle near the substrate, retract distance of needle from the substrate, and coating gap between the needle and substrate. Under the optimized coating conditions, it is demonstrated that high-aspect-ratio microlens arrays can be obtained using a coating solution with high solute concentration and a small amount of a hydrophobic solvent. It is found that the diameter and height of microlens array are decreased with increasing poly(methyl methacrylate) concentration, yet the overall aspect ratio is rather enhanced. By the addition of 5 wt% hexylamine in 35 wt% poly(methyl methacrylate) solution, we have achieved a spherical microlens with the height of 7.7 ㎛ and the width of 94.24 ㎛ (the aspect ratio of 0.082). To estimate the capability of light extraction by the microlens array, we have performed ray tracing simulations and demonstrated that the light extraction efficiency of organic light-emitting diode is expected to be enhanced up to 24%.

• Journal of the Optical Society of Korea
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• 제18권5호
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• pp.569-573
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• 2014

We demonstrate a low-cost, superbly efficient way of etching for the nano-, and micro-sized pyramid patterns on (100)-oriented Si wafer surfaces for use as a patterned master. We show a way of producing functional optical films for the viewing angle direction brightness-enhancement of Lambertian LED (light emitting diode)/OLED (organic light emitting diode) planar lighting applications. An optimally formulated KOH (Potassium hydroxide) wet etching process enabled random-positioned, and random size-distributed (within a certain size range) pyramid patterns to be developed over the entire (100) silicon wafer substrates up to 8" and a simple replication process of master patterns onto the PC (poly-carbonate) and PMMA (poly-methyl methacrylate) films were performed. Haze ratio values were measured for several film samples exhibiting excellent values over 90% suitable for LED/OLED lighting purposes. Brightness was also improved by 13~14% toward the viewing angle direction. Computational simulations using LightTools$^{TM}$ were also carried out and turned out to be in strong agreement with experimental data. Finally, we could check the feasibility of fabricating low-cost, large area, high performance optical films for commercialization.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 하계학술대회 논문집
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• pp.282-283
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• 2009

In the research, we have proposed a novel encapsulation with simple process and steady film for external environment in comparison with conventional encapsulation method. This was designed to cover the emitting organic material from air. Silicon 야oxide was used for thin film of encapsulation and the deposition thickness of the organic film was 220 nm. Operating voltage of green OLED with encapsulation was 5.5 V and luminance was 7.370 cd/$m^2$ at the applied voltage of 14.5 V. Luminance was measured in 10 hour intervals at the air-exposed condition. After 110 hours and 300 hours, luminances of green OLED were 7,368 and 7,367 cd/$m^2$, respectively. Luminance of green JLED doesn't decrease until 300 hours. As a results, proposed encapsulation can increase the life time of green OLED.

• 마이크로전자및패키징학회지
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• 제15권2호
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• pp.1-6
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• 2008

고효율 녹색 인광 유기발광다이오드를 개발하기 위해 소자 구조를 ITO/2-TNATA/NPB/TCTA/CBP:$7%Ir(ppy)_3$/BCP/SFC-137/LiF/Al로 설계 제작하고 그 전계발광 특성을 평가하였다. 소자 제작에서 발광 호스트의 두께를 $150{\AA}{\sim}350{\AA}$ 범위로 변화시켜, 전계발광 특성을 비교해 본 결과, CBP두께가 약 $300{\AA}$ 부근일 때 가장 우수한 휘도 특성이 얻어졌다 전류 효율은 CBP두께가 $300{\AA}{\sim}350{\AA}$범위일 때 거의 포화되어 최대로 나타났다. $CBP(300{\AA}):7%Ir(ppy)_3-EML$ 층을 갖는 PhOLED(phosphorescent organic light emitting diode)의 전류 밀도, 휘도, 그리고 전류 효율은 10V의 인가전압에서 각각 $40mA/cm^2,\;10000cd/m^2$, 25cd/A로 나타났다. 또한 이 소자의 최대 전류효율은 $160cd/m^2$의 휘도 상태에서 40.5cd/A로 나타났다. 발광 스펙트럼은 512nm의 중심 파장과 약 60nm의 FWHM(Full Width Half Maximum)을 나타내었으며, CIE (Commission Internationale de I'Eclairage)도표 상에서 색 좌표는 (0.28,0.63)으로 나타났다.

• 한국전기전자재료학회논문지
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• 제24권10호
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• pp.817-821
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• 2011

We have proposed an optical thin film and micro lens to improve the luminance of organic light emitting device. The first method, optical thin film was calculated refractive index of dielectric layer material that was modulated refractive index of organic material, ITO (indium tin oxide)and glass. The second method, microlens was applied with lenses on the organic device. Optical thin films were designed with Macleod Simulator and Micro Lenses were calculated by FDTD (finite-difference time-domain) solution. The structure of thin film was designed in organic material/ITO/dielectric layer/glass. The lenses size, height and distance were 5 ${\mu}m$, 1 ${\mu}m$, 1 ${\mu}m$, respectively. The material of micro lenses used silicon dioxide. Result, The highest luminance of OLED which applied with microlens was 11,185 $cd/m^2$, when approval voltage was 14.5 V, applied thin film was 5,857 $cd/m^2$. The device efficiency applying microlens increased 3 times than the device which does not apply microlens.